DE102021130810A1 - Fibre-reinforced plastic composite with improved UV and gloss properties, a manufacturing process thereof and its use - Google Patents

Abstract

The invention relates to a fiber-reinforced plastic composite with improved UV properties, a production method thereof and its use.

Description

The present invention relates to a fiber-reinforced, multi-layer plastic composite, a production method thereof and its use.

Fibre-reinforced plastic panels are panels made of composite material. This composite material can be formed, for example, by a reinforced polymer resin matrix in which fibers are embedded. Due to the fibers that provide reinforcement to the polymer matrix, fiber-reinforced plastic products generally have higher specific stiffness as well as higher mechanical strength compared to non-reinforced polymer materials.

The term “plate” is advantageously understood to mean a planar, level structure of the reinforced polymer matrix.

The fibre-reinforced panels often prove to be disadvantageous, especially outdoors, since they are exposed to environmental influences, in particular UV radiation and different weather conditions without protection. These environmental influences result in the reinforced polymer matrix being gradually degraded and/or destroyed. This in turn has the consequence that both the aesthetic appearance and the mechanical properties of the fiber-reinforced panels suffer and deteriorate significantly over time and increasing environmental influences. In the worst case, the environmental influences can render the fiber-reinforced product completely unusable. For example, increased brittleness, a significant loss of gloss and/or a clear yellowing of the polymer matrix can be attributed to environmental influences and UV exposure and the associated aging process of the fiber-reinforced plastic sheets.

Task

It is therefore the object of the present invention to provide a plastic composite which has a higher gloss stability than the known fiber-reinforced plastic products from the prior art.

Furthermore, it is the object of the present invention to provide a plastic composite which does not yellow even after long periods of use under environmental influences.

Furthermore, it is the object of the present invention to provide a plastic composite which satisfies high quality requirements and in which defects are reduced.

Furthermore, it is the object of the present invention to provide a plastic composite which has a lower weight than known fiber-reinforced plastic panels.

Furthermore, it is the object of the present invention to provide an optimized plastic composite which has consistent mechanical properties.

Furthermore, it is the object of the present invention to provide a plastic composite with improved resistance to erosion in comparison to known fiber-reinforced plastic panels.

Solution

This is implemented with a fiber-reinforced, multi-layer plastic composite according to patent claim 1.

The core of the invention lies in providing a fiber-reinforced, multi-layer, flat plastic composite with improved UV resistance, which has at least one matrix layer for forming a supporting matrix body and also at least one top layer arranged on the matrix layer, which acts as a surface seal for the matrix layer and/or is formed as a UV protective layer of the matrix layer, the matrix layer having at least one resin from the group of unsaturated polyester resins, vinyl ester resins, epoxy resins, polyurethane resins and/or combinations thereof and the top layer having at least one acrylate-based resin, the top layer being deep-curing when exposed to UV light and wherein at least the matrix layer is fiber-reinforced.

Surprisingly, it has been shown that such a plastic composite has numerous improvements over the prior art.

Thus, the top layer, which has at least one unsaturated, aliphatic resin based on acrylate, protects the matrix layer arranged underneath from UV damage and the effects of the weather. In addition, such a resin proves to be advantageous since it can be crosslinked in a short time with UV exposure. This prevents irregularities in the top layer.

Furthermore, it has surprisingly been shown that the layer thickness of the top layer with the material composition based on acrylate described here can have a significantly reduced thickness, in order nevertheless to protect the underlying matrix material accordingly.

Furthermore, with the plastic composite described here, a significantly reduced overall weight is obtained compared to known fiber-reinforced panels from the prior art. In this way, a weight reduction of up to 100 g can advantageously be achieved with the plastic composite described here, based on an area of 1 m ² . Consequently, the plastic composite described here is particularly suitable to be used advantageously in lightweight construction, in the construction sector for building facades, in transport for truck bodies or in leisure vehicles in the caravanning sector.

An aliphatic resin is advantageously understood to mean a resin which lacks an aromatic backbone. This is advantageous because this resin can be crosslinked by exposure to UV light without destroying the basic structure. In particular, it has surprisingly been shown that this works particularly well with an unsaturated aliphatic resin based on acrylate.

“Acrylate-based resin” can advantageously be understood to mean any type of acrylic resin and/or acrylate resin.

It has been shown to be advantageous that the top layer in the finished end product has a particularly high color stability and also a particularly high gloss stability. For the entire plastic composite, this means that, as a fiber-reinforced plastic composite, it has significantly improved UV and weather resistance. The material of the matrix layer selected from the group consisting of unsaturated polyester resins, vinyl ester resins, epoxy resins, polyurethane resins and/or combinations thereof is advantageously to be understood as the base layer material of the matrix layer.

The matrix material is selected in such a way that sufficient flexibility in the cured state is advantageously required. Here, resins with an elongation at break in the range of 1.5 - 3.0% ( DIN EN ISO 527-4/2/2 ) proven. Lower elongations at break increase the risk of damage due to cracking. A higher elongation at break leads to an overall material with less rigidity, which proves to be clearly disadvantageous for the processing of the resulting plastic composite. This is usually further processed into sandwich elements using different pressing processes. A less rigid material would tend to show through the inner sandwich construction, whereby the surface is usually uneven and dented.

In addition to the elongation at break of the resin, the heat resistance provided is also important. If this is selected too low, heat deformations in the plastic composite can occur when using dark materials, which cause a higher heat load. Resins have therefore proven to be particularly suitable which have at least a heat resistance according to ISO 75 Method A of 60°C. Particularly suitable resins are between 70 - 90°C. The matrix material is particularly advantageously selected from the group consisting of polyester resins, vinyl ester resins, epoxy resins, polyurethane resins and/or combinations thereof.

Further advantageous embodiments result from the following dependent claims.

In a further advantageous embodiment, it has proven advantageous for the top layer to have at least one deep-curing UV initiator. This proves to be advantageous, since when exposed to UV radiation, the crosslinking process does not begin on the surface of the material, but in the volume below. Consequently, it can be achieved for the first time that precisely the exposed surface directly exposed to UV radiation is not fully cured. It is also found to be advantageous if the UV initiator is susceptible to oxygen inhibition since the reaction is then slowed down. The free radicals formed are acidified by the free radical character of the air toffs before they can start polymerisation. The slower reaction at the boundary layer allows the top layer to be chemically crosslinked with the matrix layer and advantageously leads to a permanent bond between the matrix layer and the top layer. The plastic composite described here has very good bonding properties between the top layer and the matrix layer. A loss of adhesion, for example in the form of flaking or cracks, is not observed.

The UV initiator is required to start the radical polymerization when exposed to UV radiation. It should be noted here that no crosslinking takes place without UV exposure. This proves to be particularly advantageous when storing and preparing the outer material, since it can be used for a long time despite being mixed. Consequently, with the exclusion of UV rays, the pot lives are particularly long, from several days to several months, advantageously up to 12 months. "Pot life" is generally understood to mean the length of time that two or more components which are reactive with one another, for example resin and hardener, remain usable after mixing.

In a further advantageous embodiment, it has proven advantageous for the deep-curing UV initiator to have at least one phosphine oxide group. Phosphine oxides, for example diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide (Omnirad TPO), ethyl-(2,4,6-trimethylbenzoyl)phenylphosphinate (Omnirad TPO-L) or phenylbis-(2 ,4,6-trimethylbenzoyl)phosphine oxide (Omnirad 819) proved to be advantageous. This phosphine oxide group can be cured and crosslinked with long-wave UV radiation. On the free upper side, from where the UV radiation is introduced, the radicals formed are bound with atmospheric oxygen. Networking is inhibited. Away from the free upper side, i.e. in the upper layer volume below, the crosslinking can take place much better. Therefore, the phosphine oxide group introduced here in the top layer can form deep hardening.

Furthermore, a deep-curing UV initiator, advantageously selected from the phosphine oxide group mentioned above, proves to be advantageous if the top layer has at least one further additive, for example a color pigment. Due to the long-wave excitation of the UV initiators disclosed here, the UV radiation introduced into the top layer is not absorbed by the color pigment and is therefore completely available for the polymerization of the top layer. As a result, a colored top layer can be crosslinked and hardened to a high quality for the first time.

TPO-L has proven to be a particularly advantageous UV initiator, since this composition can already be provided in the liquid state of aggregation. The other two compositions, Omnirad 819 and Omnirad TPO, are in the solid state and must first be converted to the liquid state before use.

If the top layer applied is then exposed to at least one UV radiation source, a curing gradient is formed. Directly on the surface of the top layer, where the UV radiation hits, the conversion to crosslinking is low and increases in the direction of the layer thickness progression. This means that lower-lying areas of the top layer have a significantly higher conversion during crosslinking.

Furthermore, deep curing has the advantage that the top layer remains flat during the manufacturing process. For example, if the depth hardening were not carried out sufficiently, the top layer would delaminate during the manufacturing process, so that the production had to be stopped, since a top layer with corrugations and delamination would be unusable. Insufficient deep curing and thus unusable top layers can be observed, for example, with initiators such as methyl benzoyl formate or 1-hydroxycyclohexyl phenyl ketone or also when using acetophenones or benzophenones.

In a further advantageous embodiment, the acrylate-based resin of the top layer can be a urethane acrylate resin. This may be referred to as the base layer material of the top layer. This has an aliphatic backbone which has a large number of carbamate groups. The basic structure also has at least one methacrylate group and/or one acrylate group as a free end group. Networking takes place via this group. As a result of the crosslinking, a urethane acrylate network is formed in which the individual oligomers interact with one another with the aliphatic basic structure, the carbamate groups arranged thereon and the at least one crosslinking group. The stability of the network is obtained via the crosslinkable acrylate groups and/or methacryl groups of the oligomers. The carbamate groups of one oligomer can be reversibly hydrogen bonded to others bind carbamate groups of other oligomers. This combination means that the top layer remains sufficiently flexible even after crosslinking, and cracks and breaks are prevented.

Furthermore, the at least one acrylate-based resin is advantageously designed to be photoinitiable, so that the crosslinking takes place by free-radical polymerisation when exposed to UV light. This also has the advantage that crosslinking can take place in extremely short time intervals, with a homogeneous surface structure and overall structure of the top layer being achieved at the same time. The upper layer, which is to be deep-cured by means of UV exposure, is exposed to UV radiation in a time interval of 3-30 seconds, more advantageously 5 to 15 seconds. This very short time interval is sufficient for the deep-curing crosslinking of the top layer to develop. This enables particularly fast crosslinking, which means a particularly large amount of time is saved for the entire production process. The time saving is accompanied by a cost reduction and the market success can be increased.

In a further advantageous embodiment, the material of the upper layer can be mixed with further reactive monomers. Such monomers can be 1,6-hexanediol diacrylate (HDDA) and/or trimethylolpropane triacrylate (TMPTA). By adding reactive monomers to the acrylate-based resin, the properties of the top layer, especially with regard to its flexibility, can be changed in a targeted manner. For example, the flexibility of the top layer in the cured state can be increased by adding 1,6-hexanediol diacrylate (HDDA) and/or trimethylolpropane triacrylate (TMPTA). This makes the top layer less susceptible to deep scratches and damage. 1,6-Hexanediol diacrylate (HDDA) and/or trimethylolpropane triacrylate (TMPTA) can be understood as reaction solvents.

In a further advantageous embodiment, the matrix layer can have at least one type of fibers as reinforcement material. The selected reinforcement material and thus the type of fibers advantageously depends on the planned use of the plastic composite produced. For example, carbon fibers, glass fibers, polymer fibers, basalt fibers and/or combinations thereof are possible. The fibers introduced into the matrix layer serve to reinforce the matrix layer when external forces are applied, for example due to torsional forces caused by the driving of leisure vehicles or commercial vehicles, by impact loads on the campsite or in road traffic or by weather events such as hail or strong winds.

The fibers can be embedded in the matrix layer, for example as chopped glass fibers, chopped glass mats, glass roving fabrics, multiaxial fabrics and/or combinations thereof. Glass fibers in particular have proven to be particularly advantageous as a reinforcing material due to the simple processing and high reinforcing properties.

The reinforcement material introduced is particularly advantageously a semi-finished textile product. This can be, for example, chopped glass mats, glass roving fabrics, multiaxial fabrics and/or combinations thereof.

If, for example, a cut glass mat is used as reinforcement material in the production of the plastic composite described here, it can be unwound continuously during the production process and first placed on top of the liquid matrix layer material. The cut glass mat is well wetted by the capillary forces. Optionally, additional impregnation aids can be provided in order to accelerate and improve the impregnation. The cut glass mat is absorbed by the still liquid matrix layer.

It is also conceivable, depending on the use of the finished plastic composite, that, for example, several identical and/or several different fiber reinforcement materials are embedded in the matrix layer. For example, it is conceivable that a number of cut glass mats, a number of multiaxial fabrics and/or a number of glass roving fabrics are embedded in the matrix layer.

In this way, the reinforcement effect caused by the respective reinforcement material can be adjusted in a targeted manner.

Of course, it is also conceivable that more than one cut glass mat is introduced into the matrix layer, which is still to be hardened. Advantageously, the cut glass mats are discharged one after the other and from above, with a time offset. The staggered application of several cut glass mats ten has the advantage that the still liquid resin remains intact as a layer and the cut glass mats can be impregnated one after the other via capillary forces.

The random arrangement of the glass fibers in length and width of the cut glass mat results in an open structure. Exactly this structure is advantageous so that the cut glass mat can dip into the still liquid matrix layer material. If the structure were too close-meshed, air inclusions would occur in the layer structure. Due to the very open structure of the cut glass mats used here, their impregnation is supported and the formation of pores due to air inclusions is avoided. The cut glass mats are applied from above into the already applied, still liquid matrix layer material, so that the cut glass mats can dip into the liquid matrix material.

If, on the other hand, a cut glass mat with four times the thickness of a conventional cut glass mat were to be applied, applying it from above into the still liquid matrix layer would displace the still liquid resin of the matrix layer and the layer would be destroyed and become completely unusable.

It has proven particularly advantageous if the cut glass mats used here are provided as endless mats. This then advantageously has endlessly long fibers which are deposited statistically over the width and length of the mat. This results in an open structure. Exactly this structure is advantageous so that the cut glass mat can dip into the still liquid matrix layer material. If the structure were too close-meshed, air inclusions would occur in the layered structure. The very open structure of the cut glass mats used here supports impregnation and the formation of pores due to air inclusions is avoided.

The finished plastic composite advantageously has a glass content of 15 to 65% by weight, based on the total weight of the cured plastic composite. This ensures that the matrix layer is adequately reinforced while at the same time maintaining a corresponding flexibility. This is particularly necessary during assembly, as otherwise the cut edges would splinter when cutting the endless plastic composite.

If the matrix material is hardened, the fibers arranged in it are correspondingly fixed. This fixes the entire structure of the matrix material. A transformation is no longer possible. In particular, by fixing the fibers in the matrix layer, the fiber reinforcement is formed in such a way that mechanical stress is transferred to the fibers, so that a high specific rigidity and a high mechanical strength of the resulting plastic composite can be achieved.

Cut glass mats with a fiber fineness of 12 to 30 tex have proven particularly advantageous. When using this fineness of fiber, a high level of surface evenness of the matrix layer can be produced.

In a further advantageous embodiment, at least one separating layer can be arranged between the top layer and the matrix layer. This at least one separating layer can be designed as a glass fleece, for example. This separating layer has the task of creating a separation between the top layer and the fibers of the matrix layer. On the one hand, this can prevent fibers in the manufacturing process from damaging the deep-hardened top layer and causing significant defects.

In addition, the fibers embedded in the matrix layer form a structure at the interface with the top layer, which is referred to as a fiber imprint. The fiber imprint is visible through the top layer in the finished plastic composite. This fiber imprint is absolutely undesirable, especially when using the plastic composite in the caravanning sector. High quality requirements are placed on the wall elements of caravans and/or mobile homes, so that a visible fiber imprint represents a reduction in quality or a defect. If the glass fleece advantageously has a thickness in the range of 150-250 μm, the fiber imprint visible through the top layer is spanned and its optical visibility is significantly reduced. Advantageously, the glass fleece has a grammage in the range from 15 to 35 g/m ² . The above-mentioned proportion of glass in the finished plastic composite is to be understood as the total proportion of glass. This includes the glass portion of one or more glass fleeces.

The at least one separating layer is therefore used to create an optical separation between the top layer and fibers in the matrix layer. At the same time, the fiber impression is spanned and thus reduced. The plastic composite described here has at least one fiber imprint-reducing separation layer when used as a caravan wall element and/or mobile home wall element.

In a further advantageous embodiment, the matrix layer is formed from an unsaturated polyester resin and/or a vinyl ester resin, both of which have unsaturated groups. In order to initiate the free-radical polymerization of the unsaturated groups, the matrix material advantageously has at least one organic peroxide, which decomposes when exposed to temperature. In addition, a crosslinking agent can also be provided in the matrix material, which causes the crosslinking of the respective resin. Styrene can be used as an example of such a crosslinker.

In addition to its function as a crosslinker, styrene also acts as a solvent for the resin in question. For example, by using an unsaturated polyester resin and/or vinyl ester resin, covalent bonds can be formed to the unsaturated aliphatic resin of the topsheet.

In a further exemplary embodiment of the present invention, the matrix material can also be an epoxy resin and/or a polyurethane resin. Both resins have no unsaturated groups. When using this kind of resins, it is necessary to start polyaddition as a polymerization reaction. In this case, any type of molecule containing reactive oxygen can be used to crosslink the resin. This includes, for example, amines, acids, acid anhydrides, alcohols and/or thiols and combinations thereof. If epoxy resin and/or a polyurethane resin is used as the matrix material, this will form a non-covalent bond with the top layer. This is done in that both resin materials of the two layers are at least partially dissolved at the interface, which leads to a non-covalent interaction between the top layer and the matrix layer.

In a further advantageous embodiment, the top layer and/or the matrix layer can have at least one further additive. The additive can advantageously be selected from the group of coloring additive, effect pigment, UV initiator, UV stabilizer, radical scavenger and/or a combination thereof.

In one embodiment, it has proven to be advantageous if both the matrix layer and the top layer each have at least one coloring additive. It is conceivable that the upper layer and the matrix layer each have at least one coloring pigment. The plastic composite is dyed through so that any possible external damage to the top layer, such as a scratch, is almost unnoticeable.
Consequently, with the at least one coloring pigment, minor damage to the plastic composite can be optically compensated in an excellent manner. The finished plastic composite, ie its two layers, is advantageously colored throughout with the same coloring pigment.

Depending on the use of the plastic composite, titanium dioxide, for example, exhibits a particularly good white coloring effect. As a result, the layer containing the titanium dioxide is colored white. In addition to titanium dioxide, there are also, for example, barium sulphate or zinc sulphide which can be mentioned as coloring pigments. These also require a white coloring of the respective layer.

Of course, this is not to be understood as limiting, so that it is also conceivable that one and/or both layers are colored black, for example by adding carbon.

In addition, it is also conceivable to specifically color the matrix layer and/or the top layer by adding further coloring pigments and/or dyes according to the intended use. Here, for example, blue dyes have also proven to be advantageous since they can already be provided in the matrix material and/or top layer material that is kept available. Mixtures of dyes and color pigments and/or of color pigments with one another are also possible. For example, a gray matrix layer and/or top layer can be produced by mixing titanium dioxide and carbon. The mixing ratio depends on the desired gray level.

The coloring of both layers is an example here, but is to be understood as being particularly advantageous. It is also conceivable, depending on the application, to add different coloring additives to the top layer and the matrix layer.

If color pigments are used, it has proven to be advantageous to introduce them in the liquid state in the range from 1 to 15 phr, based on the respective layer. Color pigments added to the top layer in this range provide sufficient protection against yellowing of the matrix layer. In addition, the top layer is still deep-curable.

The addition of titanium dioxide to the top layer has proven to be particularly advantageous if the plastic composite is to be colored white. In order to be able to ensure adequate curing of the top layer and to avoid folds during curing, it has been shown to be advantageous to select the pigment content of titanium dioxide in the range from 1.5-8 phr. If, for example, a titanium dioxide content of more than 8 phr is used, the hardening of the top layer is adversely affected. The upper layer is pre-hardened, causing the surface to fold up while the sub-surface underneath remains liquid. A titanium dioxide content of more than 8 phr should therefore be avoided. The advantage of titanium dioxide and other coloring additives is that the pigment itself and/or its absorbent character protects the underlying matrix layer and prevents it from yellowing. The coloring additives, such as color pigments, effect pigments and/or dyes, are thus designed as UV reflectors and/or UV filters for the underlying, non-UV-resistant matrix layer.

In a particularly advantageous embodiment, the plastic composite disclosed here shows that the liquid top layer can have a color pigment content of 3 to 8 phr and through the simultaneous provision of a deep-curing UV initiator, which the top layer also has at least, a top layer colored by color pigment can also be targeted for the first time can be hardened and crosslinked. If conventional, i.e. no deep-curing, UV initiators were used, the applied UV radiation would be almost completely reflected by the color pigment and no crosslinking would take place. A high-quality curing of a colored top layer has therefore been implemented for the first time in combination with at least one deep-curing UV initiator.

If, for example, the top layer has a titanium dioxide content of 3-8 phr, it has also proven advantageous to also provide the matrix layer with the coloring pigment. Due to the low layer thickness of the top layer in combination with the titanium dioxide content in the range of 3-8 phr, the top layer shows transparency. This means that 100% opacity cannot be created. It has therefore proven to be advantageous to also color the matrix layer accordingly. A white, through-colored plastic composite results. This in turn has the advantage, as already explained above, that scratches are less visible overall and even deep scratches do not come to the fore optically.

This is also particularly important for the caravanning sector, since the plastic composites used to date yellow significantly over time, which significantly reduces and degrades the resale value and of course the visual appearance.

At the same time it has been found that the small proportion of at least one coloring pigment in the top layer has no effect on its hardening or on the later optical effect of the top layer.

Furthermore, at least one effect pigment can also be used in the top layer and/or in the matrix layer. It is conceivable, for example, to provide at least one effect pigment in the top layer. As a result, for example, their reflection can be greatly increased, resulting in a glittering optical effect.

Examples of such effect pigments which have proven advantageous are, for example, glass particles, mica and/or layered silicate particles. These can optionally be coated with at least one or more of the following oxides: titanium dioxide, iron oxide, silicon dioxide and/or tin oxide.

It is also conceivable to select the effect pigments from aluminum particles, copper particles, brass particles or bronze particles and/or combinations thereof. This allows special metallic effects to be created. In addition, it has been shown to be advantageous that by using particles in the top layer, their scattering effect can be exploited, so that incoming UV radiation is reflected by the top layer, more precisely by the particles introduced therein. This provides additional UV protection for the underlying matrix layer, preventing it from yellowing.

The effect pigments particularly advantageously have an average particle size in the range from 10-100 μm. The particle size of the effect pigments is defined as the d ₅₀ value, which is determined by laser granulometry. The d ₅₀ value indicates the average particle size of the effect pigments, with 50% of the effect pigment particles in the sample examined being smaller than the stated value.

The coloring additives, effect pigments and dyes of any kind can therefore advantageously be combined as coloring additives. These can be contained in the top layer and/or in the matrix layer.

Of course, the exemplary embodiments here are not to be understood as limiting. Combinations of effect pigment, for example mica (mica), with color pigment, for example titanium dioxide, in mixing ratios of 1:1, 1:2 or 1:3 are also advantageous. Top layers with optical effects and additional UV protection can then be provided here.

It is also conceivable that the top layer can have one or more UV stabilizers, UV initiators and/or one or more free-radical scavengers as further additives. Depending on the selection and proportion, this can further improve the UV and weather resistance of the entire plastic composite.

In a further advantageous embodiment, the top layer can have a layer thickness in the cured state in the range from 40 to 150 μm. The cured top layer more advantageously has a layer thickness of between 50 and 110 μm. Layer thicknesses of 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 105 μm and 110 μm and all areas in between have proven to be advantageous. since reduced layer thicknesses require less material consumption and can be cured quickly overall. At the same time, it has been shown that the top layer described here can be produced without defects despite the small layer thickness, as mentioned above. In particular, the resulting hardened top layer is free of fat spots, free of thick spots, free of folds, free of underhardening and free of matting effects and the like. It is now possible for the first time to provide such a top layer in the layer thicknesses mentioned here without defects over a length of 180 m in a continuous process.

Due to the extremely small layer thickness, it is possible for the plastic composite products produced to have a higher glass content and thus also better mechanical properties with the same thickness than has been possible with the prior art up to now. Alternatively, it is also conceivable to save weight by reducing the layer thickness.

In addition, it is also conceivable that the plastic composite can have a higher glass content of up to 65% by weight. It is thus possible for a plastic composite produced in this way with a high glass content of up to 65% by weight to have a tensile strength of around 400 N/mm ² ( DIN EN ISO 527-4/2/2 ) and tensile modulus of about 23,000 N/mm ² ( DIN EN ISO 527-4/2/2 ) may have.

In a further advantageous embodiment, the top layer, which is advantageously in the form of urethane acrylate, can have a maximum loss of 2% by weight in the cured state compared to the liquid state. This loss is due to the reaction solvent, e.g. HDDA. This is released during curing. The extremely low shrinkage of the top layer is particularly advantageous, since this allows material to be saved, thereby reducing production costs.

In a further advantageous embodiment, the top layer has a gloss retention of at least 80% after 3000 hours of XENOTEST.

It has been shown to be advantageous that the urethane acrylate used as the top layer of the plastic composite can be colored to a certain extent with color particles, with the curability by UV radiation being maintained.

It has also been shown to be advantageous that these coloring additives block the majority of UV radiation, advantageously >95% of the incoming radiation, in outdoor applications to such an extent that it does not reach the underlying matrix layer with the fiber reinforcement. See Table 1, in which a gallium-doped mercury lamp was used as the UV radiation source. The top layer with different pigment content was placed on a radiometer type Power Puck 2 and passed under the UV lamp with 120 W/cm at 10 m/min. Table 1: UV puck UV Puck Without pigment UV Puck 0.75 wt% pigment UV - Puck 1.50 wt% pigment UV Puck 3.0 wt% pigment UV-A 255 mJ/cm ² : 64 mJ/cm ² : 11 mJ/ ^cm2 : 0 0 UV B 300 mJ/cm ² : 7mJ/ ^cm2 : 0 0 0 UV-C 65 mJ/cm ² : 1mJ/ ^cm2 : 0 0 0

As can be seen from Table 1, the addition of 1.5% by weight or more of pigment, for example titanium dioxide, to the top layer provides UV protection for the underlying matrix layer against yellowing. When radiating through the top layer, no more UV radiation is detected below the top layer. If only 0.75% by weight of pigment is added, it can be seen that the reduced UV radiation is transmitted through the top layer. In the long term, this would also lead to yellowing of the non-UV-resistant matrix layer underneath.

The matrix layer of the plastic composite described here is free of UV stabilizers, so that it quickly turns yellow when exposed to UV light. So-called yellowing occurs.

With the present invention, an overall system was created for the first time as a plastic composite made of fiber-reinforced plastic, almost any color selection and maximum UV stability, which prevents yellowing over the years.

The UV resistance of the top layer and/or the plastic composite and/or the matrix layer can be evaluated using the color change properties (color measurement space L/A/B and color change Delta E) and the loss of gloss. The plastic composite is subjected to a predetermined dose of UV radiation over a defined period of time using a xeno test DIN EN ISO 4892-2-A1 exposed. Will this xeno test after DIN EN ISO 4892-2-A1 carried out for 3000 hours, the top layer of the plastic composite has a gloss retention of at least 80%.

It has been shown that the upper layer of the plastic composite described here has a gloss loss of <10% in a xeno test according to DIN EN ISO 4892-2-A1 over 1000 hours. If the Xeno test according to DIN EN ISO 4892-2-A1 is carried out for 7000 hours, which corresponds to 15 to 20 years of outdoor exposure in a Central European climate, the top layer of the plastic composite described here only shows a loss of gloss of <30%. This means that the plastic composite described here for the outside area is of particularly high quality and has a long service life. Even after 15-20 years, the gloss of the top layer is essentially retained, so that the plastic composite can continue to be used and does not have to be exchanged and replaced.

Furthermore, it has been shown to be advantageous that the plastic composite described here in a 1000h xeno test DIN EN ISO 4892-2-A1 a Delta E value of <1.0 and in a 3000h xeno test EN ISO 4892-2 has a Delta E value of <1.7. With this test, it must be taken into account that with a Delta E value of ≥ 3, there is a subjectively perceptible color change. Yellowing can therefore be ruled out even after decades.

These data were determined using a Konica Minolta CM-2600d spectrophotometer (illuminant D65), with the color measurement space being specified as L = 44, a = -1.35 and b = -2.35.

The data determined via the spectrophotometer DIN EN ISO 4892-2-A1 are in 1 and 2 shown.

1 shows the behavior of the plastic composite (dashed) described here under artificial weathering DIN EN ISO 4892-2-A1 as color change (yellowing) (y-axis) over time (x-axis). The plastic composite described here, which advantageously has at least 1.5% by weight of pigment and a maximum of 8% by weight of pigment, for example titanium dioxide, in the top layer, advantageously in the form of urethane acrylate, is shown as a dashed line. It can be seen that the yellowness increases only very slowly over time to a value of 1.5.

In comparison, the solid line shows the same plastic composite only without color pigment in the top layer. It can be seen that the yellowing of the matrix layer sets in particularly quickly.

In 2 is the loss of gloss (y-axis) after artificial weathering DIN EN ISO 4892-2-A1 plotted over time (x-axis). The plastic composite described here, which advantageously has at least 1.5% by weight of pigment and a maximum of 8% by weight of pigment, for example titanium dioxide, in the top layer, advantageously in the form of urethane acrylate, is shown as a solid line. It can be seen that the loss of gloss decreases only slightly over the years. After around 9000 hours of XENOTEST, the gloss level remains at around 80% of the originally new 100% gloss level.

The dotted line shows a comparison of the same plastic composite with a top layer according to the previous standard (isophthalic acid-based polyester resin with neopentyl glycol). It can be seen that after a very short time, around 1000 hours, the loss of gloss is more than 80%.

The plastic composite described here can be produced particularly advantageously in a width of 1.5 m-4 m and with a length of up to 250 m in an endless process. This 250 m length is due to the packaging of the ready-rolled plastic composite. The manufacturing process itself is designed as a continuous process.

Furthermore, the invention also relates to a production method for producing the plastic composite according to patent claim 10.

1. a. Aufbringen des Oberschichtmaterials auf eine Trägeroberfläche;
2. b. Formen des Oberschichtmaterials zu einer Schicht auf der Trägeroberfläche;
3. c. Beaufschlagen der entstandenen Oberschicht mit UV-Strahlung, so dass die Oberschicht tiefenhärtet;
4. d. Aufbringen des Matrixmaterials zur Ausbildung der Matrixschicht;
5. e. Aufbringen von Fasermaterial auf die Matrixschicht, wobei das Fasermaterial in die noch flüssige Matrixschicht einsinkt und/oder das Fasermaterial durch Kapillarkräfte von der noch flüssigen Matrixschicht umschlossen wird;
6. f. Härten der Matrixschicht;
7. g. Entfernen des Trägermaterials, um den faserverstärkten, mehrlagigen Kunststoffverbund als Endprodukt zu erhalten.

The method includes at least the following steps:

1. a. applying the topsheet material to a support surface;
2. b. forming the topsheet material into a layer on the support surface;
3. c. subjecting the resulting top layer to UV radiation so that the top layer hardens in depth;
4. i.e. applying the matrix material to form the matrix layer;
5. e. Application of fibrous material to the matrix layer, the fibrous material sinking into the still liquid matrix layer and/or the fibrous material being surrounded by the still liquid matrix layer by capillary forces;
6. f. hardening of the matrix layer;
7. G. Removal of the carrier material in order to obtain the fiber-reinforced, multi-layer plastic composite as the end product.

In a first step a), the liquid top layer material that is still to be cured is applied to a support surface. In an advantageous exemplary embodiment, it has proven to be advantageous if the carrier surface itself is in the form of a film. In particular, it has proven to be advantageous if a polyethylene terephthalate (PET) film is used as the carrier surface, to which the top layer material that is still to be hardened is applied. Polyethylene terephthalate is advantageous in that the top layer material does not form a permanent adhesive bond with it, and the film can be removed again accordingly easily and without destroying the top layer in the later production process.

It has also been shown to be advantageous if the PET film has a film thickness in the range of 10-350 μm.

The top layer material to be applied is advantageously in the form of an unsaturated, aliphatic resin based on acrylate. Furthermore, additives can be provided, such as coloring additives, UV stabilizers, UV initiators, reactive accelerators and free-radical scavengers and/or combinations thereof. These additives are advantageously added to the top layer material before application to the support surface.

The formation of the carrier surface as a PET film is of course not to be understood as limiting, so that it is also conceivable that other carrier surfaces are used. For example, a possible geometric shape could also be used as the carrier surface. It is also conceivable that belt-like transport surfaces are used.

In order to eliminate possible creases in the PET film, which can result from its manufacturing process or winding, it has proven advantageous in one embodiment if the PET film is preheated before the top layer material is applied. Temperatures in the range of 40-80° C. have proven advantageous here. This exposure to heat is sufficient so that possible folds can be smoothed out while the PET film is being unwound, ie while the carrier surface is being prepared. This can be done, for example, by applying a tensile force in a uniaxial and/or biaxial direction.

In the next process step b), the surface material that is still to be hardened is adjusted to the desired layer thickness. The layer structure of the plastic composite, starting with the top layer, makes it possible to adjust and control its properties in a particularly simple and targeted manner. The layer thickness of the top layer material that is still to be hardened is set using a doctor blade. The layer thickness set here corresponds to the top layer that is deep-hardened in the next step.

It should be noted that the layer thickness set here is selected in such a way that the layer thickness in the deep-hardened state in step c), taking account of volume shrinkage, is in the range from 40 to 150 μm, advantageously in the range from 90 to 110 μm. Advantageously, the top layer applied here only shows a volume shrinkage of between 0.5-4% based on the original volume.

In method step c), the top layer material is now exposed to UV radiation. A gallium-doped UV radiation source can be used for this purpose, for example. In order to achieve particularly effective and even deep curing, the UV radiation is emitted from above and hits the free surface of the top layer. Consequently, the top layer is exposed to UV radiation from behind, based on the later layer structure of the plastic composite.

Deep networking is initiated. The deep-hardened upper layer forms. This also has the advantage that the side of the top layer facing away from the radiation, which forms a continuous common contact area with the carrier surface, remains smooth and even. The structure of this common contact area is determined by the structure of the carrier surface. In the later plastic composite end product, this common contact surface is the visible surface, which is also directly exposed to the effects of the weather and UV radiation.

The hardening process can also be controlled by irradiating the upper layer from the rear. This is achieved through the combination with a deep-curing UV initiator, for example from the group of phosphine oxides. As a result, controlled deep curing can be provided for the first time in the manufacturing process of thin layers. Only 80-50% of the free surface of the upper layer, which is directly exposed to the UV radiation, is converted. As the layer thickness progresses in the direction of the support surface, the proportion of conversion increases. A crosslinking conversion of more than 90% can advantageously be achieved at the interface between the carrier surface and the top layer. As a result, the later visible surface is hardened and thereby stabilized. Later folds in the production process can therefore be ruled out. However, the free surface remains only partially hardened. This has the advantage that the top layer remains chemically reactive on the free surface.

Optionally, it is possible that before and/or in and/or after the UV exposure area, the temperature of the carrier material with the top layer applied is controlled. For this purpose, temperature-controllable plate elements for guiding the carrier material can be arranged underneath it. The plate elements can be understood as supporting surfaces over which carrier material with a top layer is guided. These can dissipate a possible temperature input, which can result during UV radiation, quickly and in a controlled manner. This prevents the carrier material from melting.

Furthermore, it is optionally conceivable that the carrier material with a liquid top layer is already preheated before UV exposure. This can have a positive effect on the flatness of the carrier film, so that wrinkling of the upper layer arranged thereon is prevented during the subsequent hardening.

This proves to be particularly advantageous when the matrix layer material is applied in the next step d). Due to the still chemically reactive outer surface of the top layer, to which the matrix material is applied at least partially, advantageously completely, in chemical interaction with it can occur. For example, it is conceivable for the top layer and the matrix layer to interact covalently or non-covalently with one another. As a result, the adhesion properties of the two layers to one another can be significantly improved.

It is also conceivable that the two layers are later covalently bonded to one another via a free-radical polymerization reaction.

In the next method step d), the matrix material is applied to form the matrix layer. The matrix material is applied to the top layer. A layer adjustment can take place, for example, analogously to the surface layer. In one embodiment, it is conceivable that the layer thickness of the matrix layer can be predetermined using a doctor blade.

Following this, in the next method step e), the reinforcing material is introduced into the matrix layer. Woven or non-woven textiles, laid nets, mats, short fibers or other fibers can be introduced as fiber reinforcement material. Different fiber types can be used for this, such as glass fibers, carbon fibers, basalt fibers and/or polymer fibers, such as aramid fibers, and combinations thereof.

In a particularly advantageous embodiment, glass fibers have proven to be particularly advantageous since, in addition to cut fibers, they can also be used as semi-finished textile products, advantageously as prefabricated cut glass mats. These chopped glass mats are particularly advantageous in that they have a fixed distribution of glass fibers within 1 square meter. The fibers are fixed with a binder, which prevents the fibers from shifting during impregnation. In the case of cut glass, displacement cannot be avoided. Furthermore, due to the existing cutting technology, the distribution of the glass is significantly less precise, which results in poorer evenness of the surface and provides less consistent and reliable reinforcement. Therefore, semi-finished textile products, advantageously cut glass mats, are advantageously used in the plastic composite described here.

In addition, the cut glass mats have proven to be advantageous in that they can be introduced over the entire matrix layer and are thus distributed evenly. In the case of the statistical cut fiber distribution, this is precisely difficult, since there are often uneven accumulations of cut fibers. This then adversely affects the quality of the matrix layer. This often also leads to high product rejects.

The glass fibers used are advantageously E-glass, which is used for electrical applications or plastic reinforcements. E-glass can advantageously be understood to mean aluminoborosilicate glass which is essentially free of alkali metal oxides. Of course, this is not to be understood as limiting, so that any other type of glass can also be used here as a reinforcing material.

Therefore, in a particularly advantageous embodiment of the method described here, cut glass mats are used for fiber reinforcement of the plastic composite. These cut glass mats are introduced into the not yet hardened matrix layer. Due to the capillary forces and the planar formation of the cut glass mats, advantageously over the entire production width of the matrix layer, the cut glass mats sink slowly and in a controlled manner into the matrix layer. The cut glass mat dives in, so to speak, and is saturated with the matrix material. As a result, the cut glass mat is impregnated at the same time.

This controlled feeding of the cut glass mats into the matrix layer that is still to be hardened and their coarse formation completely avoids air inclusions. Due to the capillary forces and the coarse structure of the cut glass mats, possible air pockets are transported upwards and escape from the matrix layer. Consequently, a high-quality matrix layer results, which is hardened in the next step f).

Of course, the use of chopped glass fibers and/or chopped glass mats is not to be understood as limiting, so that carbon fiber mats or polymer fiber mats, for example, can also be used instead of the chopped glass mats.

Curing in process step f) is advantageously carried out thermally. Depending on the choice of matrix material, in particular whether it still has unsaturated groups, the top layer and mat rixschicht covalently or non-covalently interact with each other, so as to form an interconnected layer structure as a composite.

If the matrix material is selected from the group consisting of unsaturated polyester resin, vinyl ester resin, epoxy resin and/or polyurethane resin and/or at least one combination thereof, the layered composite is thermally cured. Of course, this is not to be understood as limiting, so that further hardening options are also available.

Depending on the later use, the matrix layer, in which the reinforcement material is already arranged, can have a layer thickness in the hardened state in the range of 0.3-5 mm.

In the last step g), the carrier surface is removed. If this is designed as a film, for example, the film can simply be pulled downwards from the plastic composite and rolled up again, for example.

The end product can then be assembled. It is advantageously designed like a plate.

If the plastic composite is intended for special applications, it is conceivable that, for example, the side with the outer matrix layer is treated further. This can be, for example, increasing the adhesive properties, or a corona treatment and/or flame treatment to adjust the wettability and polarity of the surface.

The top layer, on the other hand, remains as manufactured.

Finally, the side surfaces of the plastic composite can optionally be polished. As a result, improved installation options can be achieved when used as facade components.

In a further advantageous embodiment, it has been shown to be advantageous that the method described here is in the form of a continuous method. As a result, plastic composites up to 4 m wide and up to 250 m long can be produced in a short production time.

In a further advantageous embodiment, it has been shown to be advantageous that at least between steps c) and d) a further step is interposed, in which at least one separating layer is applied to the deep-hardened top layer. The separating layer serves in particular to reduce the fiber imprint, which can later be formed by the fiber reinforcement of the matrix layer. The separating layer can advantageously be introduced as a glass fleece and prevents an above-average impression of the glass fibers at the interface between the top layer and the matrix layer.

In a further advantageous embodiment, it has been shown that at least between steps e) and f) a further carrier material is applied to cover the matrix layer. In the simplest case, this carrier material can be designed as a film, even more advantageously as a PET film. It is conceivable that the carrier material for covering the matrix layer is the same as the carrier material for applying the top layer. This additional cover is used for improved hardening and defect reduction during the entire production process.

In a further advantageous embodiment, an additional process step can be carried out between step f) and g). This step can be performed as a UV post-cure step of the topsheet from the exposed backside of the substrate. In the intermediate process step, the upper layer is post-cured. As already explained above, the top layer has so far only been deep-hardened. With the subsequent post-curing, which takes place by exposure to UV radiation, the upper layer can be cured completely. In particular, the common contact surface between the top layer and the matrix layer is still reactive and not fully cured and crosslinked. The advantage of this post-curing is that a significant reduction in crack resistance can be achieved.

It has therefore proven advantageous to carry out a post-curing step. It has proven to be particularly advantageous and effective here if the UV radiation is applied from below. This means that the UV radiation source is located below the layer structure described here is arranged. As a result, the exposure to UV radiation is introduced through the carrier surface directly onto the top layer. This proves to be particularly advantageous since the entire matrix layer material with the embedded fiber reinforcement does not have to be exposed to UV radiation. As a result of the exposure to UV radiation directed from below, this can produce an advantageously complete deep crosslinking and hardening of the top layer at the interface to the matrix layer in a particularly short time. After 3 to 15 seconds, the upper layer is hardened with the above layer thicknesses. As a result, the manufacturing process is designed to save time and money.

Furthermore, the present invention relates to the use of a plastic composite according to the present invention as a surface component for the interior and / or exterior lining of vehicles, aircraft, trains, ships, caravans, mobile homes, as a surface element for logistics and transport, for example for truck bodies, as a facade element in the construction industry. This creates value retention, since there is almost no visual impairment due to yellowing of the plastic composite.

Furthermore, the invention also relates to a plastic composite which is produced according to the aforementioned production method.

The plastic composite described here can be produced over large square meter areas for the first time. For example, it is possible for the plastic composite to have an area of at least 1 m x at least 1 m, at least 1 m x 1.5 m, at least 1.5 m x 1.5 m, at least 1 m x at least 2 m, at least 2 m x at least 2 m, of at least 2 m x at least 4 m. The plastic composite advantageously has a flat shape. Depending on the use, the plastic composite can be in the form of sheets or rolls. As a result, large areas can be clad with the plastic composite described here without it being necessary to separate them into pieces. This creates a particularly aesthetic appearance when in use.

Furthermore, it has been shown that the top layer based on a urethane acrylate resin is initially no higher

Surface hardness of the plastic composite itself. However, the low layer thickness of the top layer means that the high hardness of the matrix material has a greater impact. At the same time, this increases the quality. For example, if a dirt particle is pressed into the top layer, it can be displaced less because of the thin layer. This means that the impression is significantly weaker. This is particularly advantageous since the plastic composite described here is often further processed later using pressing methods. Here, dirt particles can often occur between the press surface and the plastic composite. Consequently, due to the low layer thickness, the indentations due to the applied pressure of dirt can be significantly reduced. A pressure of between 1.5 and 4 t/square meter is often used. As a result, significantly less waste is produced due to the pressed-in dirt.

The invention described here advantageously has high UV resistance while maintaining the degree of gloss and almost no change in color. This can be achieved in particular by the coloring additives in the top layer.

Furthermore, the coloring additives, advantageously the color pigments, have proven to be advantageous since they protect the underlying matrix layer, which is not UV-stabilized and is formed, for example, from an unsaturated polyester and/or epoxy resin, from UV radiation and thus prevents yellowing .

• - Kurzfasermatten: Festigkeit ca. 60 N/mm² | E-Modul ca. 6.000 N/mm²
• - Gewebeverstärkung: Festigkeit ca. 150 N/mm² | E-Modul ca. 10.000 N/mm²
• - Gelegeverstärkung biaxial: Festigkeit ca. 400 N/mm² | E-Modul ca. 23.000 N/mm²
• - Gelegeverstärkung uniaxial: Festigkeit ca. 1.000 N/mm² | E-Modul ca. 45.000 N/mm²
• - Gelegeverstärkung uniaxial Carbonfasern: Festigkeit ca. 1.300 N/mm² | E-Modul ca. 110.000 N/mm².

Furthermore, it has been shown that the mechanical properties of the plastic composite described here can be adjusted by a factor of 15-20 by using different fiber reinforcements. A range of properties results DIN EN ISO 527-4/2/2 :

• - Short fiber mats: strength approx. 60 N/mm ² | Modulus of elasticity approx. 6,000 N/ ^mm2
• - Fabric reinforcement: strength approx. 150 N/mm ² | Modulus of elasticity approx. 10,000 N/ ^mm2
• - Biaxial scrim reinforcement: strength approx. 400 N/mm ² | Modulus of elasticity approx. 23,000 N/ ^mm2
• - Reinforcement uniaxial: strength approx. 1,000 N/mm ² | Modulus of elasticity approx. 45,000 N/ ^mm2
• - Fabric reinforcement uniaxial carbon fibers: strength approx. 1,300 N/mm ² | E-module approx. 110,000 N/mm ² .

Further advantages, features and design options result from the exemplary embodiments, which are not to be understood as limiting. The wording "essentially" means a deviation in the range of 1% to 20%, more advantageously 1% to 10%, even more advantageously 1%, in all cases used here in which this formulation is used within the scope of the present invention. up to 5% of the definition that would have been given without the use of this wording.

Detailed description of exemplary embodiments

The indication "phr" is to be understood as parts by weight related to 100 parts of the respective base layer material of top layer or matrix layer in the liquid state.

1. External caravan side wall

In the exemplary embodiment of a caravan exterior wall described here, the end product produced has a total thickness of 1.5 mm ± 0.1 mm and has a total width of 2.8 m. Since the manufacturing process is designed as an endless process, the product length is variable and can be tailored according to customer requirements.

First, a liquid surface material is applied to a biaxially stretched film, advantageously a PET film. Immediately afterwards, the layer thickness is set to 110 µm ± 15 µm using a squeegee. The PET film serves as a carrier material and can itself have a thickness of 10-400 μm, with a PET film thickness of 100 μm having been found to be particularly advantageous. It is sufficiently stable to serve as a carrier film and still sufficiently thin for the UV radiation required for UV crosslinking to pass through. The surface material can advantageously be formed to contain at least one urethane acrylate.

• 100 phr Urethaneacrylat (Laromer UA9089)
• 0,5 phr Hostaphin 3058 LIQ
• 0,5 phr Tinuvin 1130 als UV-Absorber
• 4 phr Titandioxid
• 1,5 phr TPO-L als tiefenhärtender UV-Initiator

oder

• 100 phr Urethaneacrylat (Ebercryl IRR 1032)
• 0,5 phr Hostaphin 3058 LIQ
• 0,5 phr Tinuvin 1130 als UV-Absorber
• 4 phr Titandioxid
• 1,5 phr TPO-L als tiefenhärtender UV-Initiator

The applied surface material in this embodiment can have the following compositions:

• 100 phr urethane acrylate (Laromer UA9089)
• 0.5 phr Hostaphine 3058 LIQ
• 0.5 phr Tinuvin 1130 as UV absorber
• 4 phr titanium dioxide
• 1.5 phr TPO-L as a deep-curing UV initiator

or

• 100 phr urethane acrylate (Ebercryl IRR 1032)
• 0.5 phr Hostaphine 3058 LIQ
• 0.5 phr Tinuvin 1130 as UV absorber
• 4 phr titanium dioxide
• 1.5 phr TPO-L as a deep-curing UV initiator

After the layer thickness has been adjusted, the liquid surface material applied to the carrier material is exposed to at least one UV radiation source from above. The UV entry thus takes place directly via the exposed surface of the surface material layer. A gallium-doped mercury lamp is advantageously used as the UV radiation source for this purpose. This advantageously has a UV dose of 400 mJ/cm ² ±10%.

The PET film designed as the carrier material also has the task of preventing oxygen inhibition at the film/surface material interface. As a result, a high crosslinking conversion of >90% is achieved in the area of this interface. The free surface, on the other hand, is in contact with the air and is oxygen-inhibited. This leads to a degree of crosslinking of 50 to 80% of the free surface.

In deeper layers, which are not affected by the oxygen inhibition of the hardener radicals, a degree of crosslinking of usually >90% is achieved (measured with IR-ATR; calculation via the peak area of the CC double bond). In this regard, it should be stated that IR-ATR is in a range of 400 - 4000 Wave number (cm ^-1 ) light radiates onto a sample. Radiation is absorbed at the surface due to the covalent bonds present before the remainder is reflected back to the device. The decrease in the double bond is relevant for the crosslinking measurement. The double bond creates its own specific peak at about 809 cm ^-1 . Here the Lambert-Beer law applies, which means that the peak area is directly proportional to the concentration of the binding.

Therefore, the liquid sample is measured first and the area under the measured peak is integrated. This area corresponds to a degree of crosslinking of 0% or 100% non-crosslinked bonds. After hardening, one integrates again, the area again indicates how many bonds have not yet been crosslinked. The difference between the two corresponds to the degree of crosslinking achieved.

In a next step, the matrix material is applied to the at least partially UV-cured exposed surface of the surface material. The layer thickness of the matrix material can be adapted to later use. In the present exemplary embodiment, a layer thickness of approx. 1100 μm is selected. The layer thickness is set using another doctor blade.

• 100 phr ungesättigtes Harz, vorteilhaft das mittelreaktive, orthophthalsäurebasierende Matrixharz Palatal P4 L21
• 5 phr Titandioxid
• 0,15 phr Cobaltbeschleuniger 1%ig
• 1,7 phr Härter, vorteilhaft Curox I300

In the example described here, the matrix material has the following composition:

• 100 phr unsaturated resin, advantageously the medium-reactive, orthophthalic acid-based matrix resin Palatal P4 L21
• 5 phr titanium dioxide
• 0.15 phr cobalt accelerator 1%
• 1.7 phr hardener, preferably Curox I300

For example, solvents such as styrene, xylene, TXIB, 2-ethylhexan-1-ol with a corresponding cobalt content can be used as cobalt accelerators.

In the present exemplary embodiment, reinforcing materials are introduced into the matrix material that has been drawn off. Due to the still liquid state of aggregation of the matrix material, the reinforcing materials can sink into the matrix material layer and are essentially completely, advantageously completely, surrounded by it. The reinforcement material is thereby impregnated at the same time.

Cut glass mats are usually selected as the reinforcing material for the application mentioned in this exemplary embodiment. The cut glass mat has a grammage of 375 g/m ² .

As an alternative to the chopped glass mats, chopped fibers can also be used for reinforcement.

To reduce the fiber print of the chopped fibers and/or chopped glass mats, at least one separating layer is advantageously arranged between the top layer and the chopped fibers and/or the chopped glass mat before the matrix layer is applied. The separating layer is advantageously designed as a glass fleece. The glass fleece used here also advantageously has a grammage of 20 g/m ² . This brings improved stability and prevents the individual cut glass fibers and/or the glass fibers of the mats from being pressed into the top layer and, in the worst case, protruding through it from the plastic composite. In addition, the interface between the top layer and the fibers is more even and the fiber structure is optically covered and minimized.

• - Oberschicht
• - Separationsschicht, vorteilhaft ein Glasvlies
• - Matrixschicht mit eingelassener Schnittglasmatte

In the exemplary embodiment described here, the structure of the individual layers is as follows:

• - upper class
• - Separation layer, advantageously a glass fleece
• - Matrix layer with embedded cut glass mat

Finally, another carrier film, advantageously a PET film, is advantageously applied to the matrix layer. This prevents oxygen inhibition during the curing of the matrix material. The entire layer system is calendered to remove air pockets between the PET film and the resin.

The matrix material is then heated to 100° C. for 20 minutes to harden it at high temperatures. The resulting plastic composite is then cooled back down to room temperature.

In order to crosslink the upper layer containing urethane acrylate, the plastic composite is again exposed to UV radiation. This can be done with another UV radiation source that emits a dose of 400 mJ/cm ² . This radiation source is arranged below the layer system in the production process and thus acts first on the carrier surface and then on the top layer. There is thus an irradiation from below.

In the penultimate step, the two carrier foils, which previously limited the area of the plastic composite, are then removed. The plastic composite is then assembled. It has been shown that a plastic composite produced in this way has a tensile strength DIN EN ISO 527-4/2/2 of 70 N/mm ² and a tensile modulus of elasticity DIN EN ISO 527-4/2/2 of 6,000 N/mm ² .

In the exemplary embodiment described here, the resulting plastic composite has a glass content of 20-30% by weight.

The plastic composite described here with both possible top layer alternatives shows a significantly increased gloss retention, almost no yellowing and a weight reduction of about 100 g / m ² compared to known fiber-reinforced plastic panels with improved mechanical properties. In particular, the significant reduction in yellowing and maintenance of the degree of gloss over decades, determined via Xeno-Test DIN EN ISO 4892-2-A1 (see above) is enormously relevant for value retention in the caravanning sector. For example, if the caravan still looks like new after 15 years, shiny white and not matt yellowed, this creates a significantly higher resale value.

2. Commercial vehicle outer side wall

In the second exemplary embodiment described here, the end product produced, that is to say the plastic composite, is used for an outer side wall of a commercial vehicle. The plastic composite produced according to this second exemplary embodiment has a total thickness of 1.4 mm±0.1 mm and a total width of 2.4 m. Since the manufacturing process is designed as an endless process, the product length is variable and can be tailored according to customer requirements.

First, a liquid surface material is applied to a biaxially stretched film, advantageously a PET film. Immediately afterwards, the layer thickness is set to 110 µm ± 15 pm using a squeegee. The PET film serves as a carrier material and can itself have a thickness of 10-400 μm, with a PET film thickness of 100 μm having been found to be particularly advantageous. It is sufficiently stable to serve as a carrier film and still sufficiently thin for the UV radiation required for UV crosslinking to pass through. The surface material can advantageously be formed to contain at least one urethane acrylate.

• 100 phr Urethanacrylat (Laromer UA9089)
• 0,5 phr Hostaphin 3058 LIQ
• 0,5 phr Tinuvin 1130 (UV-Absorber)
• 4 phr Titandioxid (bei abgetönten Weißtönen bzw. Farben können mehr Pigmenttypen hinzukommen)
• 1,5 phr TPO-L

oder

• 100 phr Urethanacrylat (Ebercryl IRR 1032)
• 0,5 phr Hostaphin 3058 LIQ
• 0,5 phr Tinuvin 1130 (UV-Absorber)
• 4 phr Titandioxid (bei abgetönten Weißtönen bzw. Farben können mehr Pigmenttypen hinzukommen)
• 1,5 phr TPO-L

The applied surface material in this embodiment can have the following compositions:

• 100 phr urethane acrylate (Laromer UA9089)
• 0.5 phr Hostaphine 3058 LIQ
• 0.5 phr Tinuvin 1130 (UV absorber)
• 4 phr titanium dioxide (more pigment types can be added for tinted whites or colors)
• 1.5 phr TPO-L

or

• 100 phr urethane acrylate (Ebercryl IRR 1032)
• 0.5 phr Hostaphine 3058 LIQ
• 0.5 phr Tinuvin 1130 (UV absorber)
• 4 phr titanium dioxide (more pigment types can be added for tinted whites or colors)
• 1.5 phr TPO-L

After the layer thickness has been adjusted, the liquid surface material applied to the carrier material is exposed to at least one UV radiation source from above. The UV entry thus takes place directly over the exposed surface of the surface material layer. A gallium-doped mercury lamp is advantageously used as the UV radiation source for this purpose. This advantageously has a UV dose of 400 mJ/cm ² ±10%.

The PET film designed as the carrier material also has the task of preventing oxygen inhibition at the film/surface material interface. As a result, a high crosslinking conversion of >90% is achieved in the area of this interface. The free surface, on the other hand, is in contact with the air and is oxygen-inhibited. This leads to a degree of crosslinking of 50 to 80% of the free surface.

In deeper layers, which are not affected by the oxygen inhibition of the hardener radicals, a degree of crosslinking of usually >90% is achieved (measured with IR-ATR; calculation via the peak area of the C-C double bond - for measurement and evaluation, see example 1 - caravan outer wall).

In a next step, the matrix material is applied to the exposed surface of the applied and at least partially cured top layer material. The layer thickness of the matrix material can be adapted to later use. In the exemplary embodiment disclosed here, the matrix advantageously has a layer thickness in the range of approximately 700 μm.

• 100 phr Biresin LXR 121
• 26 phr Biresin LXH 121-3

The matrix layer is advantageously formed to contain at least one epoxy resin and has the following composition:

• 100 phr Biresin LXR 121
• 26 phr Biresin LXH 121-3

The applied epoxy resin is applied to the back of the top layer, which is partially hardened here, and drawn off with a squeegee with a layer thickness of about 700 μm.

In the present exemplary embodiment, reinforcing materials are introduced into the matrix material that has been drawn off. Due to the still liquid state of aggregation of the matrix material, the reinforcing materials can sink into the matrix material layer and are essentially completely, advantageously completely, surrounded by it. The reinforcement material is thereby impregnated at the same time.

• - Oberschicht
• - Matrixschicht mit
  • - einem ersten Biaxialgelege mit einer Grammatur von 812gr/m²
  • - einem zweiten Biaxialgelege mit einer Grammatur von 812gr/m²

In the exemplary embodiment described here, the structure of the individual layers is as follows:

• - upper class
• - Matrix layer with
  • - a first biaxial fabric with a grammage of 812 g/m ²
  • - a second biaxial fabric with a grammage of 812 g/m ²

The biaxial fabrics used are textile semi-finished products that have biaxially arranged glass roving strands. The advantage of this biaxial fabric is that more glass can be provided in the resulting plastic composite with the same thickness. As a result, additional mechanical properties can be achieved at a lower weight. A low coefficient of thermal expansion also goes hand in hand with the use of these biaxial non-crimp fabrics.

Finally, another carrier film, advantageously a PET film, is advantageously applied to the matrix layer. This must be suitable for being able to be demoulded by the matrix layer, ie the epoxy resin which forms the matrix layer in this exemplary embodiment. The entire layer system is calendered to remove air pockets between the PET film and the resin.

The matrix material is then heated to 100° C. for 30 minutes for temperature hardening. The plastic composite is then cooled back down to room temperature.

In order to crosslink the upper layer containing urethane acrylate, the plastic composite is again exposed to UV radiation. This can be done with another UV radiation source that emits a dose of 400 mJ/cm ² . This radiation source is arranged below the layer system in the manufacturing process and thus acts directly on the top layer. There is thus an irradiation from below.

In the penultimate step, the two carrier foils, which previously limited the area of the plastic composite, are then removed. The plastic composite is then assembled. It has been shown that a plastic composite produced in this way has a tensile strength DIN EN ISO 527-4/2/2 of 400 N/mm ² and a tensile modulus of elasticity DIN EN ISO 527-4/2/2 of 23,000 N/mm ² .

The plastic composite described here shows a significantly increased gloss retention, almost no yellowing and a weight reduction of up to 100 g / m ² compared to known fiber-reinforced plastic panels with improved mechanical properties. In particular, the significant reduction in yellowing and maintenance of the degree of gloss over decades, determined via Xeno-Test DIN EN ISO 4892-2-A1 (see above) is enormously relevant for the value retention of truck bodies. If, for example, the truck body still looks like new after 15 years, shiny white and not matt yellowed, this creates a significantly higher resale value. There is a high resistance to erosion.

3. Curtain wall panel for the construction industry

In the third exemplary embodiment described here, the plastic composite produced according to this exemplary embodiment is used as a curtain wall panel, for example in the construction industry. The plastic composite produced, i.e. the end product, has a total thickness of 5.0 mm ± 0.15 mm and a total width of approx. 2.4 m. Since the manufacturing process is still designed as a continuous process, the product length is variable and can be tailored according to customer requirements.

First, a liquid surface material is applied to a biaxially stretched film, advantageously a PET film. Immediately afterwards, the layer thickness is set to 110pm ± 0.15pm using a squeegee. The PET film serves as a carrier material and can itself have a thickness of 10-400 μm, with a PET film thickness of 100 μm having been found to be particularly advantageous. It is sufficiently stable to serve as a carrier film and still sufficiently thin for the UV radiation required for UV crosslinking to pass through. The surface material can advantageously be formed to contain at least one urethane acrylate.

• 100 phr Urethanacrylat (Laromer UA9089)
• 0,5 phr Hostaphin 3058 LIQ
• 0,5 phr Tinuvin 1130 (UV-Absorber)
• 4 phr Titandioxid (bei abgetönten Weißtönen bzw. Farben können weitere Pigmenttypen hinzukommen)
• 1,5 phr TPO-L

oder

• 100 phr Urethanacrylat (Ebercryl IRR 1032)
• 0,5 phr Hostaphin 3058 LIQ
• 0,5 phr Tinuvin 1130 (UV-Absorber)
• 4 phr Titandioxid (bei abgetönten Weißtönen bzw. Farben können weitere Pigmenttypen hinzukommen) 1,5 phr TPO-L

The applied surface material in this embodiment can have the following compositions:

• 100 phr urethane acrylate (Laromer UA9089)
• 0.5 phr Hostaphine 3058 LIQ
• 0.5 phr Tinuvin 1130 (UV absorber)
• 4 phr titanium dioxide (additional pigment types can be added for tinted white tones or colors)
• 1.5 phr TPO-L

or

• 100 phr urethane acrylate (Ebercryl IRR 1032)
• 0.5 phr Hostaphine 3058 LIQ
• 0.5 phr Tinuvin 1130 (UV absorber)
• 4 phr Titanium Dioxide (additional pigment types may be added for tinted whites or colors) 1.5 phr TPO-L

After the layer thickness has been adjusted, the liquid surface material applied to the carrier material is exposed to at least one UV radiation source from above. The UV entry thus takes place directly via the exposed surface of the surface material layer. A gallium-doped mercury lamp is advantageously used as the UV radiation source for this purpose. This advantageously has a UV dose of 400 mJ/cm ² ±10%.

The PET film designed as the carrier material also has the task of preventing oxygen inhibition at the film/surface material interface. As a result, a high crosslinking conversion of >90% is achieved in the area of this interface. The free surface, on the other hand, is in contact with the air and is oxygen-inhibited. This leads to a degree of crosslinking of 50 to 80% of the free surface.

In deeper layers, which are not affected by the oxygen inhibition of the hardener radicals, a degree of crosslinking of usually >90% is achieved (measured with IR-ATR; calculation via the peak area of the CC double bond; for measurement and evaluation see example 1 - caravan outer wall)

In a next step, the matrix material is applied to the at least partially UV-cured exposed surface of the surface material. The layer thickness of the matrix material can be adapted to later use. In the present exemplary embodiment, a layer thickness of the liquid matrix material of approximately 3700 μm is selected. The layer thickness is set using another doctor blade.

• 100 phr ungestättigtes Harz, vorteilhaft das mittelreaktive orthophthalsäurebasierende Matrixharz Palatal P4 L21
• 5 phr Titandioxid (bei abgetönten Weißtönen bzw. Farben können weitere Pigmenttypen hinzukommen)
• 0,15 phr Cobaltbeschleuniger 1%ig
• 1,7 phr Härter (z.B. Curox 1300)

In the example described here, the matrix material has the following composition:

• 100 phr unsaturated resin, preferably the moderately reactive orthophthalic acid-based matrix resin Palatal P4 L21
• 5 phr titanium dioxide (additional pigment types can be added to tinted whites or colors)
• 0.15 phr cobalt accelerator 1%
• 1.7 phr hardener (e.g. Curox 1300)

In the present exemplary embodiment, reinforcing materials are introduced into the matrix material that has been drawn off. The reinforcement material is inserted from above. Due to the still liquid state of aggregation of the matrix material, the reinforcing materials can sink into the matrix material layer and are essentially completely, advantageously completely, surrounded by it. The reinforcement material is thereby impregnated at the same time.

Cut glass mats are usually selected as the reinforcing material for the application mentioned in this exemplary embodiment.

As an alternative to the chopped glass mats, chopped fibers can also be used for reinforcement.

To reduce the fiber print of the chopped fibers and/or chopped glass mats, at least one separating layer is advantageously arranged between the top layer and the chopped fibers and/or the chopped glass mat before the matrix layer is applied. The separating layer is advantageously designed as a glass fleece. The glass fleece used here also advantageously has a grammage of 20 g/m ² . This brings improved stability and prevents the individual cut glass fibers and/or the glass fibers of the mats from being pressed into the top layer and, in the worst case, protruding through it from the plastic composite. In addition, the interface between the top layer and the fibers becomes more even and the fiber structure is optically covered.

• - Oberschicht
• - Glasvlies mit einer Grammatur von 20g/m²
• - Matrixschicht mit
  • - erster Schnittglasmatte in einer Grammatur von 375gr/m²
  • - zweiter Schnittglasmatte in einer Grammatur von 375gr/m²
  • - dritter Schnittglasmatte in einer Grammatur von 375gr/m²
  • - vierter Schnittglasmatte in einer Grammatur von 375gr/m²
  • - Endlosmatte in einer Grammatur von 450gr/m²

In the exemplary embodiment described here, the structure of the individual layers is as follows:

• - upper class
• - Glass fleece with a grammage of 20g/m ²
• - Matrix layer with
  • - first cut glass mat with a grammage of 375 g/m ²
  • - second cut glass mat with a grammage of 375 g/m ²
  • - third cut glass mat with a grammage of 375 g/m ²
  • - fourth cut glass mat with a grammage of 375 g/m ²
  • - Endless mat with a grammage of 450g/ ^m2

The four cut glass mats used here are inserted one after the other from above into the matrix layer that is still to be hardened. One cut glass mat after the other is soaked by capillary action and surrounded by the matrix layer.

It has proven to be advantageous to insert four individual cut glass mats one after the other into the matrix layer. This requires a highly uniform distribution of the matrix material. Would, for example If only one thick cut glass mat were introduced, which would correspond to the four individual mats, the matrix layer material would be pressed out laterally and the entire plastic composite would be defective.

Finally, another carrier film, advantageously a PET film, is advantageously applied to the matrix layer. This prevents oxygen inhibition during the curing of the matrix material. The entire layer system is calendered to remove air pockets between the PET film and the resin.

The matrix material is then heated to 90° C. for 30 minutes to harden it at high temperatures. The resulting plastic composite is then cooled back down to room temperature.

In order to crosslink the upper layer containing urethane acrylate, the plastic composite is again exposed to UV radiation. This can be done with another UV radiation source that emits a dose of 400 mJ/cm ² . This radiation source is arranged below the layer system in the manufacturing process and thus acts directly on the top layer. There is thus an irradiation from below.

In the penultimate step, the two carrier foils, which previously limited the area of the plastic composite, are then removed. The plastic composite is then assembled. It has been shown that a plastic composite produced in this way has a tensile strength DIN EN ISO 527-4/2/2 of 60 N/mm ² and a tensile modulus of elasticity DIN EN ISO 527-4/2/2 of 6,000 N/mm ² .

The plastic composite described here with both possible top layer alternatives shows a significantly increased gloss retention, almost no yellowing and a weight reduction of up to 100 g/m ² compared to known fiber-reinforced plastic panels with improved mechanical properties. In particular, the significant reduction in yellowing and maintenance of the degree of gloss over decades, determined via Xeno-Test DIN EN ISO 4892-2-A1 (see above) is enormously relevant for the value retention of the facade elements. The plastic composite described here is particularly advantageous in the construction sector, where building facades should look attractive for decades. For example, facade elements can be provided that still look almost new even after decades of outdoor exposure. There is a high resistance to erosion. Expensive renovation measures or even an exchange of the facade elements is not necessary. In this way, costs can be significantly reduced.

Although the invention has been illustrated and described in more detail by the advantageous exemplary embodiments, the invention is not restricted by the disclosed examples. Other variations can be derived from this by a person skilled in the art without departing from the scope of protection of the invention. In particular, the invention is not limited to the combinations of features specified below, but other combinations and sub-combinations that are obviously executable for a person skilled in the art can also be formed from the disclosed features.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Non-patent Literature Cited

• DIN EN ISO 527-4/2/2 [0020, 0073, 0135, 0156, 0174, 0194]
• DIN EN ISO 4892-2-A1 [0081, 0083, 0085, 0086, 0088, 0158, 0175, 0195]
• DIN EN ISO 4892-2 [0083]

Claims (17)

Fibre-reinforced, multi-layer, flat plastic composite with improved UV resistance having at least a. a matrix layer for forming a supporting matrix body and furthermore b. at least one top layer arranged on the matrix layer, which is designed as a surface seal of the matrix layer and/or as a UV protection layer of the matrix layer, the matrix layer having at least one resin from the group consisting of unsaturated polyester resins, vinyl ester resins, epoxy resins, polyurethane resins and/or combinations thereof and the top layer has at least one acrylate-based resin, with at least the matrix layer being fiber-reinforced. Fibre-reinforced, multi-layer plastic composite claim 1 , characterized in that the top layer has at least one deep-curing UV initiator. Fibre-reinforced, multi-layer plastic composite claim 2 , characterized in that the at least one deep-curing UV initiator has a phosphine oxide group. Fiber-reinforced, multi-layer plastic composite according to at least one of the preceding claims, characterized in that the matrix layer also has at least one type of fibers. Fibre-reinforced, multi-layer plastic composite according to at least one of the preceding claims, characterized in that at least one further separating layer is also arranged between the top layer and matrix layer. Fibre-reinforced, multi-layer plastic composite according to at least one of the preceding claims, characterized in that the top layer and/or the matrix layer has at least one further additive. Fiber-reinforced, multilayer plastic composite according to at least one of the preceding claims, characterized in that the top layer has a layer thickness in the hardened state in the range from 40 to 150 µm. Fiber-reinforced, multi-layer plastic composite according to at least one of the preceding claims, characterized in that it contains a maximum of 2% by weight of a reactive diluent, based on the liquid layer material applied during the production process. Fibre-reinforced, multi-layer plastic composite according to at least one of the preceding claims, characterized in that the top layer has a gloss retention of at least 70% after 9000 hours of XENOTEST. Method for producing a plastic composite according to at least one of the preceding claims, having at least the following steps: a. applying the topsheet material to a support surface; b. forming the topsheet material into a layer on the support surface; c. subjecting the resulting top layer to UV radiation so that the top layer hardens in depth; i.e. applying the matrix material to form the matrix layer; e. Application of fibrous material to the matrix layer, the fibrous material sinking into the still liquid matrix layer and/or the fibrous material being surrounded by the still liquid matrix layer by capillary forces; f. curing the matrix layer applied to the top layer; G. Removal of the carrier material in order to obtain the fiber-reinforced, multi-layer plastic composite as the end product. procedure after claim 10 , characterized in that at least between step c) and step d) having a further step in which at least one separating layer is applied to the deep-hardened top layer. procedure after claim 10 , At least between step e) and step f) a further carrier material is applied to cover the matrix layer. procedure after claim 10 , characterized in that at least between step f) and g) a UV post-curing of the upper layer is carried out from the free rear side of the carrier material. Fiber-reinforced, multi-layer plastic composite produced by a method according to claim 10 . Fiber-reinforced, multi-layer plastic composite according to at least one of Claims 1 until 9 prepared by a method according to claim 10 . Fibre-reinforced, multi-layer, flat plastic composite with improved UV resistance, having at least a. a matrix layer for forming a supporting matrix body and furthermore b. at least one top layer arranged on the matrix layer, which is designed as a surface seal of the matrix layer and/or as a UV protection layer of the matrix layer, the matrix layer having at least one resin from the group consisting of unsaturated polyester resins, vinyl ester resins, epoxy resins, polyurethane resins and/or combinations thereof and the top layer has at least one acrylate-based resin, at least produced by a method according to claim 10 . Use of a fiber-reinforced, multi-layer plastic composite according to at least one of Claims 1 until 9 and/or use of a fiber-reinforced, multi-layer plastic composite produced by a method according to claim 10 after at least one of the Claims 1 until 9 , as a surface component for the interior and/or exterior cladding of vehicles, aircraft, trains, ships, mobile homes, mobile homes, as a surface element for logistics and transport, for example for truck bodies, as a facade element in the construction industry.

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